This invention relates to a method and apparatus for removing bulk material from a container, in particular, a box-shaped transport container.
Bulk goods, especially sluggishly flowing bulk goods such as diatomaceous earth, silica gel or brewing gypsum that are used as filtration agent in essential foods production and as such, have a crystalline structure, are, after production; i.e., after burning and grinding, usually packaged in sacks as a fine powder and are delivered in this fashion from the producer to the consumer; i.e., to the essential foods producers such as breweries and the like.
The consumer then opens the sacks in specially provided devices in order to transfer the bulk goods into the silo container in which the bulk goods; i.e., the diatomaceous earth, silica gel or brewing gypsum, are kept and from which the particularly required quantity can be taken.
In the entire handling procedure of such dust-like or powdery bulk goods whose grain size is so small that the bulk goods dust can penetrate into the lungs of persons unhindered, one must watch out and make sure that no dust gets into the environment so as not to endanger the health of persons who handle and use such bulk material.
The European Patent No. EP 0 713 473 B 1 discloses a system, for removing sluggishly flowing, dusty bulk goods from silo containers for their storage where, attached to the outlet area of a silo container, there is a removal means that includes a conveyor device that is arranged coaxially with respect to the axis of the container in order to convey bulk goods from the lower area of a funnelxe2x80x94which is coaxial with respect to the container axisxe2x80x94upward against the force of gravity, in other words, essentially against the direction of flow of the bulk goods in the container to a discharge area. Connected to the discharge area is a bulk material auction device in order in a dosed manner to suction bulk goods rendered flowable as a result of the conveyance process.
It is furthermore already known that to transport sluggishly flowing bulk goods, one can use pressure tanks that can be impacted with compressed air amounting to several bar in order to fluidize the bulk goods, in other words, to make it flowable. To remove bulk goods from the pressure tank, one uses a suction device that works according to the Venturi principle and that is operated with compressed air.
Such pressure tanks, of course, are basically suitable for the transport of nonpourable or poorly flowing bulk goods, but they are extremely expensive because they must be able to withstand high pressures.
The object of the invention is to provide a system and a process for removing bulk goods from a container, in particular, from a box-shaped transport container that facilitates simple and reliable removal of sluggishly flowing bulk goods also after long transportation without the need for applying any high pressures.
According to the invention, the system for the removal of bulk goods from a container thus has an air supply device with the air for the fluidization of bulk material that can be directly introduced into the bulk material in the container. This makes it possible to take bulk material that has been heavily solidified by long transportation and to mix it with air in such a way, in other words, to fluidize it, that in conjunction with the discharge technique, it will continue to flow for proper discharge.
The following is particular important here: The air supply device must at least have a pipe with an air-permeable wall that can be connected to a pressure source and that can be attached in a container area that is located in front of the discharge area where the pipe with the air-permeable wall is made from a porous sinter material.
By using such a pipe, one can make it possible in a simple manner to conduct the air over a larger area immediately into the bulk material and to loosen the latter up from the inside and to fluidize it.
To make the pipe for injection into the bulk material sufficiently stiff, an advantageous version of the invention provides the following: The pipe with the air-permeable wall is arranged in an essentially cylindrical supporting frame made up of longitudinal and circumferential bridges whose longitudinal bridges essentially run in a spiral form around the pipe with air-permeable wall.
It is particularly practical when a borehole threading is arranged on the end of the pipe with the air-permeable wall that is to be arranged in the container. By combining the borehole threading with the spiral longitudinal bridges of the supporting frame, one can considerably simplify the insertion of the pipe for air supply into the bulk material.
To improve the fluidization of the bulk material in the area in front of the discharge area, a practical feature of the invention provides the following: The air supply device has a plurality of pipes with air-permeable walls where the several pipes, provided in each case in a supporting frame, are essentially equally long and can be attached mutually parallel in the container.
To facilitate the employment of the system for the removal of bulk goods, an advantageous development of the invention provides the following: Upon each pipe in the area of its end adjoining the compressed air source, there is attached a sleeve by means of which the pipe can be fastened in a holding sleeve that is provided on an adaptor frame which can be attached to the container where, on the adaptor frame, there is provided a collection pressure chamber that can be connected to the compressed air source and to which chamber one can connect each pipe with the air-permeable wall preferably by means of a pressure line.
A particularly preferred version of the invention is distinguished by the following: The container has a lining consisting of flexible, air-impermeable material in which the bulk material is received during a shipment in a manner protected against environmental factors.
By using an invention-based lining, one can essentially employ for the shipment of bulk goods, in particular, of sluggishly flowing bulk goods such as diatomaceous earth and the like, all conventional containers, in particular, also box-shaped transport containers such as, for example, maritime containers that are used for the shipment of the most varied types of goods on ships and trucks.
In order to protect the bulk material, on the one hand, during the shipment against moisture and the like and, on the other hand, to facilitate dust-free removal, an advantageous feature of the invention provides the following: The lining has an air supply area that can be cut up or cut out and that initially is tightly closed and in each case is surrounded by an outwardly extending flexible sealing cuff where the lining furthermore has an initially tightly closed discharge area for bulk material that can also be surrounded by an outwardly extending flexible sealing cuff and that can be cut up or cut out for opening.
The following is provided in order thatxe2x80x94especially before and at the start of the removal of bulk material from the containerxe2x80x94one can control the fluidization of the bulk material: The lining in an area remote from the discharge area for bulk material has an air outlet upon which adjoins an outwardly located hose whose free end can be tightly closed up.
In order further to facilitate the removal of bulk material and to avoid a so-called bridge formation where the bulk material is supported in an arch-like manner upon the sections of the container that surround the outlet area or the removal instrument, also a so-called chimney formation where the bulk material remains standing in lateral areas of the container, there is provided a particularly practical feature of the invention in that at least two removal instruments are provided which, both regarding the outflow direction of the bulk material and regarding the force of gravity, are arranged next to each other on the outlet area of the container.
Here it is particularly advantageous when each removal instrument has its own funnel segment in which is arranged the particular conveyance device with its conveyance device arranged essentially coaxially with respect to the funnel axis.
To facilitate the universal use of the invention-based system for the removal of bulk material, it is furthermore provided in a practical manner that each removal instrument can be attached to the container by means of an adaptor frame.
The invention-based process for the removal of bulk material from a transport container where a removal instrument is attached to an outlet area of the container in which bulk material in the removal instrument is essentially conveyed against its direction of outflow out of the container into a discharge area of the removal instrument and where bulk material is sectioned out of the discharge area is distinguished by the following features: Air is so piped into the bulk material in the container that the bulk material will be fluidized where preferably there are attached at least two removal instruments, both regarding the direction of outflow of the bulk material and with respect to the force of gravity next to each other on the outlet area of the container.
The following is provided in a particularly advantageous version of the invention-based process: Air can be supplied to the discharge area of the removal instrument via an adjustable secondary air valve in order to facilitate an independent off-sectioning current where the air, supplied via the secondary air valve, is reduced the moment the bulk material has been sufficiently fluidized in the container in order to increase the bulk material discharge.
In a practical manner, air for the purpose of fluidizing the bulk material is piped into the bulk material with the help of a pipe that has an air-permeable wall in a container area that lies in front of the outlet area.
In order to improve and render more uniform the fluidization of the bulk material, in other words, the loosening and whirling of bulk material with the supplied air, it is provided according to the invention that for the purpose of injecting air into the bulk material, one employs several pipes with air-permeable walls where the several pipes for the injection of air into the bulk material essentially are equally long and are arranged parallel to each other.
The following is provided here in a practical manner: The several pipes for injecting air into the bulk material are supplied with compressed air from a common compressed air source via a collection pressure chamber.
It is particularly advantageous when, prior to the start of the actual removal of bulk material from the container, air is piped into the container to fluidize the bulk material, whereas in an area remote from the outlet area of the container, air escapes from that portion where the air, escaping from the container, is filtered and is monitored for bulk material that is carried along.